A circle is a set of all points in a plane that are equidistant from a given point in the plane known as the center of the circle. A radius (plural, radii) is a segment from the center of the circle to a point on the circle. A chord is a segment whose endpoints line on a circle. A diameter is a chord that contains the center of the circle.
A circle is a set of all points in a plane that are equidistant from a given point in the plane known as the center of the circle. A radius (plural, radii) is a segment from the center of the circle to a point on the circle. A chord is a segment whose endpoints line on a circle. A diameter is a chord that contains the center of the circle.